1. Field of the Invention
This invention pertains to the construction of basis functions. Specifically, the invention relates to constructing basis functions for spectral reflectances and illuminants based on a wavelength dependence of an optical sensor.
2. Related Background Art
Many present-day applications utilize information about the spectral characteristics of objects and illuminants. For example, computer aided design/computer aided manufacturing (CAD/CAM) applications, multi-spectral image capture devices, and spectral color-matching applications can rely on spectral data to capture, process, store and render images. While the use of spectral data can provide many advantages, such as reducing metamerism, using spectral data presents some obstacles.
In particular, accurately representing the spectral characteristics of a single object or illuminant typically requires a large number of data samplings over a range of wavelengths. In other words, the dimensionality of the data is high. Moreover, the amount of data required increases significantly when a large number of objects and/or illuminants are used in an application. Storing, manipulating, or simply moving this large amount of data results in increased memory requirements and decreased computational performance.
A well-known approach to this problem is the construction of basis functions, which allow the application to generate approximations of the spectral characteristics of an object or illuminant. In one advantage, the construction of basis functions allows the effective dimension of the data to be reduced, which can result in a memory savings and a corresponding boost in computational performance. However, while the basis functions constructed by present day methods can provide a model of an object's spectral characteristics, the model does not necessarily correlate well with the perception of a particular sensor, such as human visual perception.